• Restorative Dentistry and Endodontics
• /
• v.18 no.2
• /
• pp.413-422
• /
• 1993

The purpose of this study was to evaluate the adaptation of light cured glass ionomer cement and composite resin using all- etch technique to tooth structure. In this study, class V cavities were prepared on the buccal surfaces of 10 extracted human premolar teeth with cementum margin and teeth were randomly assigned 2 groups of 5 teeth each. The cavities of glass ionomer cement group were filled with the light cured glass ionomer cement(Fuji II LC) and the cavities of composite resin group were filled with the light cured composite resion(P - 50) using all- etch technique with All- Bond 2. The restored teeth were stored in 100 % relative humidity at $37^{\circ}C$ for 48 hours. And then, the roots of the teeth were removed with the tapered fissure bur and the remaining crowns were sectioned occlusogingivally through the center of restorations. Adaptation at tooth - restoration interface were assessed occlusally, gingivally, and axially by scanning electron microscope. The results were as follows : 1. The adaptation to enamel walls of composite resin restorations using All - Bond 2 showed better than glass ionomer restorations. 2. The adaptation to gingival and axial walls of glass ionomer restorations showed better than composite resin restorations using All - Bond 2. 3. In both groups, occlusal margins of restorations showed better adaptation than gingival margins of restorations.

• Restorative Dentistry and Endodontics
• /
• v.24 no.1
• /
• pp.136-146
• /
• 1999

The purpose of this study was to estimate the changes of marginal adaptation to the cavity floor of light-cured glass ionomer cement base after application of a composite restoration. Eighty non-carious extracted human molars were used in the present study. Circular cavities were prepared on the center of the exposed dentin surface to 0.5mm, 1.0mm, 1.5mm, 2.0mm in depth and the prepared cavities were pretreated with Dentin conditioner and filled with Fuji II LC(GC Int. Co., Japan). They randomly assigned into 3 groups according to the difference in application of a composite restoration; Group 1(control group): only glass ionomer base, Group 2: The application of a composite restoration surrounded by dentin with class I cavity over glass ionomer base after conventional dentin bonding to the exposed dentin and glass ionomer base, Group 3: The application of composite restoration not-surrounded by dentin over glass ionomer base after conventional dentin bonding to the exposed dentin and glass ionomer base. To examine the interface between cavity floor and light-cured glass ionomer cement base, each groups were sectioned vertically through the center of restorations with diamond saw and the gap size(${\mu}m$) of interface measured by SEM. The results were analyzed by using One Way ANOVA. The results were as follows: 1. Good adaptation between glass ionomer cement base and cavity floor was showed in specimens with 0.5mm, 1.0mm depth base of control group. But in specimens with 1.5mm, 2.0mm depth base of control group, the gap was measured about $15{\mu}m$, $40{\mu}m$ respectively. 2. Gap size in group 2 was significantly higher than that in control group(P<0.05). 3. Gap size in group 3 was significantly higher than that in control group and group 2(P<0.05). 4. It was possible to observe the good adaptation between glass ionomer cement base and dentin which was intermediated with 4-10${\mu}m$ hybrid layer in specimens with 0.5mm, 1.0mm depth base of control group. Cohesive fracture within cement base was observed in all specimens which had the gap between glass ionomer cement base & dentin. 5. It was possible to observe the gap formation between cement base and bonding agent and between composite resin and dentin in all specimens of group 2.

• The korean journal of orthodontics
• /
• v.25 no.2 s.49
• /
• pp.223-233
• /
• 1995

The purpose of this study was to evaluate the effects of surface conditioning with $10\%$ polyacrylic acid, etching with $38\%$ phosphoric acid, and polishing with a slurry of pumice on shear bond strengths of light-cured glass ionomer cement, chemically cured glass ionomer cement, and a composite resin to enamel, and to observe the failure patterns of bracket bondings. Shear bond strengths of glass ionomer cements were compared with that of a composite resin. Metal brackets were bonded on the extracted human bicuspids after enamel surface treatments, and samples were immersed in the $37^{\circ}C$ distilled water bath, and shear bond strengths of glass ionomer cements and a composite resin were measured on the Instron machine after 24hrs passed, and the deboned samples were measured in respect of adhesive remnant index. Scanning electron micrographs were taken of enamel surfaces after various treatments. The data were evaluated and tested by ANOVA and Duncan's multiple range test, and those results were as follows. 1. Shear bond strength of light-cured glass ionomer cement showed statistically higher than that of chemically cured glass ionomer cement. 2. Shear bond strengths of light-cured and chemically cured glass ionomer cements to enamel treated with $10\%$ polyacrylic acid and $38\%$ phosphoric acid showed statistically higher than those with a slurry of pumice. 3. According to scanning electron micrographs, enamel surface conditioned with $10\%$ polyacrylic acid is slightly etched and cleaned, that etched with $38\%$ phosphoric acid is severely etched, and that polished with a slurry of pumice is irregulary scretched and not completely cleaned. 4. After debonding, light-cured glass ionomer cement to enamel treated with $10\%$ polyacrylic acid showed less residual materials on the enamel solace than composite resin to enamel etched with $38\%$ phosphoric acid. 5. There was no significant difference in the shear bond strength of light-cured glass ionomer cement to enamel treated with $10\%$ polyacrylic acid and that of composite resin to enamel etched with $38\%$ Phosphoric acid.

• Restorative Dentistry and Endodontics
• /
• v.19 no.1
• /
• pp.45-63
• /
• 1994

128 freshly extracted human molars were used to study the interaction between dentinal smear layer removal with various agents, and the shear bond strength of a light cured glass ionomer cement to dentin. It was proposed that the removal of smear layers using acidic cleaners followed by incorporation of Fe mordant with dentin could enhanced the infiltration of monomer component in light curing glass ionomer cement and resulted in a high bond strength. For the first treatment process for removal of smear layers on the surfaces of dentin, 50 % citric acid, 10% maleic acid and 10 % phosphoric acid were used, and for the second treatment process, 15% ferric chloride, 6.8% ferric oxalate or 30% potassium oxalate were used. Distilled water was used as a control. After double sequential treatment on dentin, a light curing glass ionomer cement was bonded to dentin. After being immersed in water at 31'C for 24 hours, shear bond strengths were measured Instron testing machine(Model No.4202, USA). Surface changes were also observed using SEM (Hitachi, S-2300, Japan) after treatment process with each agents. The following conclusions were drawn : 1. Dentin surface cleaned with maleic acid and treated with ferric oxalate showed the highest bond strength with light curing glass ionomer cement. 2. Bond strengths of glass ionomer cement to dentin treated with maleic acid or citric acid were the highest, and that treated with phosphoric acid showed the lowest. 3. The effect of ferric oxalate on shear bond strength to dentin was always higher than that of ferric chloride. 4. The smear layers were clearly removed and the orifices of dentinal tubules were opened widely by the citric acid, maleic acid and phosphoric acid. 5. The orifices of dentinal tubules opened after using the first solution were closed with the treatment of ferric chloride. 6. The precipitate like crystals were formed on dentin surfaces and tubules, but a significant decrease in bond strength of glass ionomer cement to dentin surface treated with potassium oxalate.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.23 no.2
• /
• pp.347-355
• /
• 1996

The purpose of this study was to compare the bond strengths of different kinds of glass ionomer cements (GIC), which is recently increasing the clinical application in the field of pediatric dentistry and measure the repaired bond strengths in order to examine the clinical applicabilty of partial repaired cases. By using one kind of the light cured type GIC and three kinds of the chemical cured type GIC, the bond strengths of the followings were compared : unrepaired group as control, repaired conditioning group, which was treated the repaired surface using 25% polyacrylic acid and repaired non-conditioning group without surface treatment. Three point bending test was performed under Universal Testing Machine in order to measure the compressive bond strengths. The results were as follows : 1. Light cured GIC had higher bond strength than chemical cured type GIC in both of repaired and unrepaired groups. 2. In repaired cases, all of the materials decreased the bond strength when compared to the control group. In the light cured type, the bond strength of repaired conditioning group decreased 31.6%, repaired non-conditioning group decreased 40.8%. In chemical cured types, the bond strength of repaired conditining group decreased 11.8%, repaired non-conditioning group decreased 20.9%. 3. All the materials, in the case of the chemical treatment on the repaired surface using 25% polyacrylic acid had higher bond strength than untreated but, lower than control group.

• Restorative Dentistry and Endodontics
• /
• v.20 no.1
• /
• pp.362-371
• /
• 1995

The purpose of this study was to evaluate the shear bond strength between composite resin and glass ionomer cement according to surface treatment methods of glass ionomer cement. Sixty round acrylic cylinders were fabricated. And then, a round undercut cavity(8 mm diameter, 2.5mm depth) was prepared in the center of the every acrylic cylinder. After all cavities were restored by using light-cured glass ionomer cement. A total of sixty acrylic cylinders restored with glass ionomer cement were divided into 4 groups according to surface treatment methods of glass ionomer cement. The surface treatment of each group were as follows : control group : no treatment Group 1 : acid etching Group 2 : sandblasting Group 3 : air-podwer abrasive polishing The composite resin was bonded to glass ionomer cement of each specimens. And the shear bond strength was tested with a universal testing machine at a cross-head speed of 1mm/min and 500kg in full scale. The results were as follows : 1. The sandblasting group(group 2) had the highest shear bond strength with $272.50{\pm}24.96\;kg/cm_2$ and the acid etching group(group 1) had the lowest shear bond strength with $192.89{\pm}29.32kg/cm_2$. 2. The no treated group(control group) had higher shear bond strength than acid etching group(group 1) (p<0.05). 3. The sandblasting group(group 2), air-powder abrasive polishing group(group 3) and no treated group(control group) had higher shear bond strength than the acid etching group(group 1) (p<0.05). 4. The sandblasting group(group 2) and air-powder abrasive polishing group(group 3) had higher shear bond strength than the no treatment group(control group), but there was not significant(p>0.05).

• Restorative Dentistry and Endodontics
• /
• v.20 no.1
• /
• pp.372-383
• /
• 1995

The staining tendency of esthetic restorative material was very important factor for the people who are great concern about the esthetics. Most external stains were superficial and adjustable by routine prophylactic procedure. But some of these stains were remained under superficial stain. Some of these stains were accumulative on external tooth surface and it's removal alter the anatomic contour of restoration. The purpose of this study was to evaluate and compare the staining tendency of esthetic restorative materials to staining solution. In this study two glass-ionomer cements (Fuji II Glass-Ionomer Cement and Fuji II LC Glass-Ionomer Cement) and three composite resins (Sil$\ddot{u}$x Plus, APH and P-50) were evaluated and compared. Total 8 disc-shaped specimens of each material (17mm diameter, Imm thick) were immersed in coffee staining solution. These specimens were divided into one control and 3 experimental groups according to the immersion period as follows : Control: immersed in distilled water during each testing period Group 1 : immersed in staining solution for 6 hours Group 2 : immersed in staining solution for 24 hours Group 3 : immersed in staining solution for 72 hours Staining tendency was evaluated by total color difference(${\Delta}E^*$) of specimen before and after staining by spectorcolorimeteric readings (ColorQUEST Spectrophotometer, U.SA.). The results were as follows : 1. The total color differences of each testing materials were increased with time. 2. Among the experimental groups, the Fuji II Glass Ionomer Cement showed the highest total color difference(6.803) and the Silux Plus showed the lowest total color difference(1.637). 3. In comparison of glass ionomer cements, the total color difference of chemical cured glass ionomer cements(6.803) were higher than light cured glass ionomer cements(3.891) (P<0.01). 4. In comparison of composite resins, the P-50 showed the highest total color difference and the Silux Plus showed the lowest total color difference, but there was not significant difference among composite resins(P>0.05).

• Restorative Dentistry and Endodontics
• /
• v.21 no.2
• /
• pp.451-469
• /
• 1996

The purpose of this study was to investigate the effect of calcium hydroxide and glass ionomer cement fillings on the levels of $LTB_4$ and $LTC_4$ in experimentally inflamed rat dental pulp. The dental pulp in the mandibular incisor of wistar rat was irritated by cutting a 5mm deep hole in the dentin with a twist drill bur of 0.5mm diameter, without cooling. The cavities were filled with calcium hydroxide(light-cured) and glass ionomer cement(light cured). The untreated pulp served as control tissue specimen. After cavity preparations, the rat with or without various treatment were sacrificed in various time by decapitation. The dental pulp tissue were carefully removed and the concentrations of $LTB_4$ and $LTC_4$ were determined by radioimmunoassay. And pulps were examined histologically to observe inflammatory feature. The result were obtained as follows : 1. The inflammatory features of pulps were observed microscopically in all experimental groups. And degree of inflammation was decreased with time. 2. The concentrations of $LTB_4$ and $LTC_4$ for all experimental groups were significantly higher than those for control group 6 hours after cavity preparation(p<0.05). 3. The group filled with calcium hydroxide was the lowest, and the group filled with glass ionomer cement, the group of irritation in that order showed increased concentrations of $LTB_4$ and $LTC_4$ 6 hours after cavity preparation. In the concentrations of $LTB_4$, significant differences among 3 groups were noted(p<0.05). 4. The group filled with calcium hydroxide was the lowest, and the group filled with glass ionomer cement, the group of irritation in that order showed increased concentrations of $LTB_4$ and $LTC_4$ 24 hours after cavity preparation. And there were statistically significant difference in concentrations of $LTB_4$ between the group of irritation and the group filled with calcium hydroxide(p<0.05). 5. The group filled with calcium hydroxide was the lowest, and the group filled with glass ionomer cement, the group of irritation in that order showed increased concentrations of $LTB_4$ and $LTC_4$ 48 hours after cavity preparation. But no statistically difference was found (p>0.05). 6. The concentrations of $LTB_4$ and $LTC_4$ in all experimental groups were highest level at 6 hour after experiment and decreased as time progresses(correlation coefficient>0.8).

• Restorative Dentistry and Endodontics
• /
• v.19 no.1
• /
• pp.124-134
• /
• 1994

The shade of restorative materials is very important for successful restoration esthetically harmonized with the natural tooth. The purpose of this study was to evaluate the color stability and the opacity change of conventional chemical setting and visible light curing glass-ionomer cements for restorative esthetic filling. Specimens of each brand (GC Fuji II and Fuji II LC) were uniformly prepared and divided into three groups: In group l(control group), the specimens received no surface treatment; in group 2, the specimens were coated with varnish and the excess gently blown off; and in group 3. the specimens were coated with light-cured bonding resin and irradiated by a visible light curing unit for 20 seconds on both sides. All specimens were stored in distilled water at $37^{\circ}C$ and checked after for 24 hours. 2 months. 4 months, 6 months. and 8 months. The color characteristics($L^*,\;a^*,\;b^*$) and the opacity(Y%) of all the samples were measured by a spectrocolorimeter and the total color differences(${\Delta}E^*$) and opacity changes(${\Delta}Y%$) were computed. The following results were obtained : 1. The total tolor differences in all groups increased with time. 2. The total color differences of the LC groups after immersion for 8 months in distilled water at $37^{\circ}C$ were lower than those of GC groups(p<0.01), and the total color differences of the varnish or the light-cured bonding resin coated groups were lower than those of the control group with glass-ionomer cements which had no surface treatment(p<0.01). 3. In all groups the translucency decreased with time. 4. In the control group and the varnish coating group. the opacity changes of the GC groups were lower than those of the LC groups(p<0.01) and in the light-cured bonding resin coated group, there was no significant difference between the GC group and the LC group. 5. The opacity changes of the varnish or the light-cured bonding resin coated groups were lower than those of the control group(p<0.01). These results suggest that color change and opacity of conventional chemical setting and light cured glass-ionomer cement were increased with time, and the color changes and the opacity changes of a control group after immersion for 8 months in distilled water at $37^{\circ}C$ were greater than those of the varnish or the light-cured bonding resin coated groups.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.25 no.1
• /
• pp.76-92
• /
• 1998

The purpose of this study was to evaluate the possible efficacy of Nd-YAG laser as a dentin conditioner by observing the laser irradiation dentin surface under scanning electron micrograph and measuring shear bond strength of restored light-cured glass ionomer mold. Fifty intact premolars were prepared for shear bond strength tests. The teeth were randomly divided into five groups as follows; Group I. no treatment Group II. 10% poly acrylic acid, 20 sec Group III. laser treatment 2 w, 20 Hz, 2 sec Group IV. laser treatment 2 w, 20 Hz, 5 sec Group V. laser treatment 2 w, 20 Hz, 10 sec Samples of each group were restored with light-cured glass ionomer cement after dentin conditioning and then measuring the shear bond strength of each specimen were measured using universal testing machine. Additional ten premolars were prepared for SEM analysis The result from the this study can be summarized as follows. 1. Shear bond strength of polyacrylic acid-treated group (II) was significantly higher than other groups (p<0.05). 2. No statistically significant difference could be found between three laser-treated groups (III, IV, V) in shear bond strength(p>0.05) 3. According to the result of observation under SEM, Polyacrylic acid was shown to have removed the smear layer effectively and opened the dentinal tubules, whereas the laser has produced the irregular surface mainly composed of melted and fused structure. The microcracks found in laser-treated groups increased in number with irradiation time and formed the regular mesh-type in 10 sec-irradiation group. 4. The ultrastructural change of dentin surface created by laser irradiation was found to the improper for bonding of the glass ionomer restorative materials. And the lower shear bond strength of laser irradiated group might have been due to the failure to form the suit able dentin surface for the glass ionomer to penetrated into and form the proper micromechanical retention.